Electrochemical cells, such as a fuel cell, generate electricity through the electrochemical reaction of a reactant and an oxidant. An electrochemical fuel cell contains an anode and a cathode, with a proton exchange membrane between the two electrodes. A reductant is introduced at the anode and an oxidant at the cathode. A preferred fuel cell uses hydrogen (H2) as the reductant, or fuel source, and oxygen (O2) as the oxidizing agent either in pure gaseous form or combined with nitrogen as in air. During operation of the fuel cell, conductive elements proximate to the respective electrodes conduct electrons generated during the reduction-oxidation reaction occurring within the fuel cell.
A single fuel cell includes a membrane electrode assembly (MEA) which includes a proton exchange membrane (PEM) sandwiched between an anode electrode and cathode electrode, respectively. A polymer selected for use as a PEM desirably has unique characteristics including permeability to protons and electrical insulation. In practice, polymers that fulfill these requirements tend to be relatively fragile and thin, with a typical thickness of approximately 10 to 125 μm. When adding the electrodes to the PEM to form the MEA, the PEM is subjected to relatively high stress conditions including both high temperature and pressure. Since the PEM membrane is fragile, it is handled and processed carefully to minimize physical tears or thinning.
The electrodes attached to the PEM in a MEA may include finely divided catalytic particles (such as precious metals) to facilitate the respective electrochemical reactions, as well as, electrically conductive particles, such as for example, carbon. The precious metals and careful handling required during the manufacturing of the MEA are costly. Overall, the associated components and assembly related to the MEA often lead to imperfections or defects. Thus, there is a need for a method of detecting such imperfections or defects.